JEE Chemistry 2023 Question with Solution

Given: A set of compounds is to be checked for both red colouration with ceric ammonium nitrate and positive iodoform test.

Find: The number of compounds satisfying both conditions.

Ceric ammonium nitrate gives a positive test with alcohols. The iodoform test is given by compounds containing the $\mathrm{CH_3CH(OH)-}$ group or compounds oxidisable to methyl ketones.

From the structures shown in the solution image, the compounds that satisfy both tests are the secondary alcohols of the type $\mathrm{CH_3CH(OH)-R}$.

Thus, three compounds meet both conditions.

Therefore, the required numerical answer is $3$.

Given: The compounds must satisfy both tests.

Identify principle:

1. Ceric ammonium nitrate test detects alcoholic $-OH$ groups by producing a red colouration.
2. Iodoform test is positive for methyl carbinols, that is, alcohols containing the fragment

or compounds that can form a methyl ketone.

Apply to the given set:

• Compounds without an alcohol group do not satisfy the ceric ammonium nitrate test.
• Alcohols that do not contain the required $\mathrm{CH_3CH(OH)-}$ unit do not give the iodoform test.
• The structures visible in the solution image show exactly three secondary alcohols of the required type.

Conclude: Hence, the number of compounds satisfying both tests is $3$.